Peristaltic pump with tube holding mechanism

ABSTRACT

A peristaltic pump for pumping fluids through a flexible tube is described which has a quick release and engagement mechanism that permits easy and rapid removal or insertion of the flexible tube into the device. The quick release and engagement mechanism of the invention consists of a shoe mounted for vertical displacement on the body of the pump. Upward movement of the shoe engages the flexible tube holding the fluid to be pumped and locks the tube against the roller assembly containing an eccentrically mounted roller which intermittently engages the tube and forces fluid out of it. To disengage the flexible tube from the pump, the shoe is moved downward out of contact with the flexible tube.

This application is a continuation-in-part of Application Ser. No.066,759 filed June 26, 1987, now U.S. Pat. No. 4,813,855.

SUMMARY OF THE INVENTION

The present invention is directed to a peristaltic pump for pumpingfluids having a unique, quick release mechanism for inserting orremoving a flexible tube carrying the liquid which is being pumped. Oncethe flexible tube is engaged by a closure member, cam assemblies on eachside of the closure member hold the tube in place to keep it fromwalking during the pumping operation. The invention is particularlyuseful in the medical arts for pumping biological fluids such as urineor therapeutic agents in liquid form.

BACKGROUND OF THE INVENTION

Peristaltic pumps for moving fluids through flexible tubing are known inthe art and have found particular application in the medical sciencesboth for moving biological fluids and for administering therapeuticagents. Typically in such peristaltic pumps, a rotor is mountedeccentrically on a shaft so that rotation of the shaft causes the rotorto transcribe an orbital path in which it is intermittently brought intopressure contact with a flexible length of tubing to compress the tubingand thereby force liquid through the tubing. Pumps of this type are, forexample, described in U.S. Pat. No. 4,559,040 to Horres et al. whichshows a peristaltic pump having a segmented stator chamber and U.S. Pat.Nos. 4,540,351 and 4,631,007 both to Olson describing peristaltic pumpswhich are provided with hinged jaws to permit insertion and removal ofthe flexible tube carrying the liquid being pumped.

As exemplified by the prior art described above, one of the problemsencountered with peristaltic pumps is the complexity of the mechanismfor holding the flexible tubing in the pump against the rotatingpressure member. While it is necessary during the pumping operation forthe flexible tubing to be held securely in the pump against a rigidsurface so that the orbiting rotor can compress the tubing and move theliquid along within it, it is also desirable to provide a mechanismwhich permits rapid and easy removal or insertion of the flexible tubingwithout requiring complex disassembly or reassembly procedures. This isa particularly important and critical feature when the peristaltic pumpsare being employed as positive displacement pumps in a medicalenvironment either for transporting or measuring biological fluids or tometer liquid therapeutic agents since the attending physician or hisassistants are unlikely to have the time or attention to become involvedin extensive manipulative procedures and must depend on metering andvolumetric measurements from a positive displacement pump designed forthis use.

It is accordingly an object of the present invention to provide aperistaltic pump having a closure mechanism which permits quick and easyinsertion and securing of a flexible tube carrying the liquid to bepumped, the closure member being provided with cams to keep the tubefrom "walking" during the pumping operation. It is a further object ofthe present invention to provide a peristaltic pump having a releasemechanism which permits quick and efficient removal of the flexible tubefrom the pump without requiring dismantling or disassembly of the pumpstructure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view showing the elements of thepresent invention;

FIG. 2 is a front plan view showing the pump of the invention with alength of flexible tubing inserted and the pump closed and ready foroperation;

FIG. 3 is an enlarged isolated side elevational view of the cammechanism used in the present invention;

FIG. 4 is an enlarged isolated front elevational view of the cammechanism shown in FIG. 3;

FIG. 5 is an enlarged isolated side elevational view of an alternativeembodiment of a cam mechanism used in the present invention; and

FIG. 6 is an enlarged isolated front elevational view of the cammechanism shown in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

The preferred embodiment of the invention and best mode is shown inFIGS. 1 through 3 and is directed to a peristaltic pump having a slidingshoe mechanism mounted to the pump housing for quickly and easilypermitting the pump to be opened or closed for insertion or removal ofthe fluid transporting flexible tubing on which the pump acts. Morespecifically, the present invention consists of a peristaltic pumpmechanism having a motor for imparting rotational motion to a rollerassembly for engaging and compressing a length of flexible tubing tocontinuously displace fluid in the tubing. The roller assembly comprisesthree rollers mounted within a roller housing. The roller housing isdisposed on a shaft connected to the motor such that rotation of theshaft causes orbital rotation of the rollers around the shaft. Theroller assembly is mounted on a pump housing which is provided with aplurality of slots in which a shoe is slidably mounted below the rollerassembly for engaging the flexible tubing. The shoe is adapted forvertical movement relative to the roller housing in order to permiteither upward or downward displacement of the shoe to engage and hold aportion of the flexible tubing against cam mechanism mounted on thehousing which prevent the tubing from walking through the pump. Verticalmovement of the shoe is effected by means of a cam shaft having a cameccentrically mounted in a cam journal on one end and passing through avertical slot in the pump housing to engage the shoe on its other end.The cam acts against bearing surfaces of the cam journal formed in thepump housing when the cam shaft is turned to cause vertical movement ofthe shaft and associated shoe.

The invention will, however, be more fully appreciated by havingreference to the accompanying drawings FIGS. 1 through 6, FIGS. 1through 3 illustrating a best mode and preferred embodiment of thepresent invention. Directing attention to FIG. 1 of the drawings, a pumphousing 9 is shown to which an electric motor 29 and an associated gearmechanism 1 (which is well known in the art) are attached by means offlexible motor mounts 28 and associated mounting screws 2 which isolateboth noise and vibration. A circular recessed cavity 40 is defined bythe upper portion of pump body 9 to receive a roller housing 17. Theroller housing comprises a pair of circular disks or plates 31 and 32joined together by a shaft 33 of reduced diameter to define an annularslot 30. A roller 16 is mounted eccentrically within the roller housing17 by means of roller pin 13. Bearings 15 are mounted on pins 13 in therollers 16 to facilitate revolution of the rollers within the housingand spacers 14 are mounted on pins 13 on each side of rollers 16 tospace the rollers 16 in the annular slot 30 of roller housing 17. Theroller housing 17 is attached to shaft 41 which passes through bearing12 mounted in a throughgoing aperture of cavity 40 of the pump body 9.Additional spacers 11 are provided along with clip 10 to maintain theshaft and roller housing properly in alignment with the pump body 9.Rotary motion is imparted to the roller assembly 17 by means of theelectric motor 29 to which the shaft 41 is coupled by flexible coupling8. Mounted between the motor 29 and gear mechanism 1 is a switch andsensor mounting plate 3. The switch and sensor mount 3 holds rotationcounting sensor assembly 4 which is attached to the sensor mount 3 bymeans of screw 5. The rotation counting sensor assembly 4 counts therotation of the vane 7 which is attached to the coupling 8 by screw 6.The vane 7 is provided with appropriate marking indicia to register onthe counting sensor 4 as the coupling and shaft are turned by the motor.The sensor-counter is of conventional design and may sense revolutionsof the shaft either mechanically or optically.

Movement of fluid through the flexible tube 34 is imparted by rotationof the roller housing 17 which causes orbital revolution of the rollers16 with intermittent engagement and compression of the flexible tubingcontaining the fluid against the shoe 19 and cam mechanisms 50 in itsclosed position as shown in FIG. 2.

Returning to FIG. 1 of the drawings, it will be seen that the shoe 19 isprovided with a concave face which corresponds to the circularconfiguration of the roller housing 17 when the device is in the closedconfiguration shown in FIG. 2. The shoe 19 thus comprises a bodydefining an accurate inner surface which forms a crescent-shapedconfiguration adapted to engage the flexible tube. The ends of thecrescent are provided with a locking surface forming two lock pointsholding the flexible tube in place preventing the walking of the tubewhen the roller assembly is rotated. Pump housing 9 is provided withvertical slots 36 in mounting plate 42 to receive the projections 38 onthe shoe 19 which permits vertical movement of the shoe 19 against theface of place 42 of the pump housing. This vertical movement of the shoe19 permits opening and closing to engage the flexible tube with therollers 16 and roller housing 17 as shown in FIG. 2. Cam shaft 39 passesthrough the vertical slot 37 plate 42 of the pump housing 9 to engagethe shoe 19. A cam 24 is eccentrically mounted on the shaft 39, and theshaft 39 is turned along with the cam 24 by means of lever 20 whichpasses through a slot 35 in the bottom of the shoe 19 to threadablyengage the shaft 39.

Cam cover 25 is mounted on the pump body 9 by means of 3 screws 26. Thecam cover 25 retains the cam 24 in the cam journal 43 which extends fromthe rear of plate 42. Ball plunger set screw 27 is used to lock cam inclosed position. The cam journal 43 comprises two bearing surfaces 44and 45 which in connection with the cam 24 open and close the pump shoe19. Movement of lever 20 rotates the cam 24 and cam shaft 39 causingvertical displacement of the cam shaft 39 within the slot 37 andcorresponding vertical movement of shoe 19 whose projections 38 travelwithin the slots 36. Thus, by merely rotating the lever arm 20 with knob21 through the slot 35 from either its position on the left to itsposition on the right the shoe 19 is caused to slide vertically downwardto open the device for insertion or removal of the flexible tubing orslide vertically upward to lock the shoe against the roller housing 17and associated cam mechanisms 50 with the tubing compressed between theconcave inner surface of the shoe 19 and roller 16 within the annularslot 30 of the roller housing and engaged by the knurled surface 60 ofthe cam mechanism 50 and knurled surface 39 of shoe 19. A safety switch22 and safety switch set screw 23 are conveniently provided on the pumphousing to signal the locking of the cam shaft in place and preventinadvertent disengagement of the shoe and opening of the pump.

The cam mechanism 50 comprises a cylindrical barrel member 52 rotatablymounted to shaft 53 which is in turn mounted to pump housing 9. Thebarrel member 52 has an integrally formed curved arm 54 with anoutwardly extending projection 56 which serves as a finger hold to liftthe cam off of the tubing 34. The underside surface of a curved arm 54is formed with knurles 60. The knurles grab the tubing and prevent itfrom walking to the pump as the roller 16 continue to engage the tubing34. As shown in FIGS. 3 and 4, the top surface 39 of shoe 19 is knurledat 61 so that both the top and bottom surfaces of the tube are held inplace when the shoe is closed. A coiled spring number 58 is mountedaround shaft 53 and has one end secured to the shaft. The other end ofthe spring is bent around the end of curved arm 54 and engages the uppersurface of arm 54 as is more clearly shown in FIG. 4. An alternateembodiment of the cam is shown in FIGS. 5 and 6 and this embodimentutilizes a similar barrel member 52 rotatably mounted on shaft 53 with acurved arm 54 and spring 58 mounted in the same manner as shown in theprevious embodiment disclosed in FIGS. 3 and 4. The alternate embodimentdoes differ from the preferred embodiment in that the outward projection56 is cylindrical in shape rather than annular as shown in FIG. 4 andprovides a different kind of a finger grasp for release of the curvedarm 54. It should be noted that the undersurface of arm 54 is coatedwith an abrasive material 62 which engages the tubing in a similarmanner to that of the knurles 60 grab the tubing and prevent it fromwalking through the pump. It is also noted that surface 49 of shoe 19can be coated with a similar abrasive material to provide doublegrabbing action in much the same manner as the double knurled surfaces60 and 61 shown in the FIGS. 3 and 4.

In operation, once the flexible tubing 34 containing a fluid to bepumped is inserted between the concave surface of the shoe 19 and theroller housing 17, movement of the lever 20 from the open, right sideposition to the closed, left side position raises the shoe 19 and bringstubing 34 into pressure contact with rollers 16 between the shoe 19, theknurled surface 49 of shoe 19 and the cam mechanism 50. As housing 17 isturned by the motor, the rollers 16 transcribes an orbital motion whichintermittantly brings rollers 16 into pressure contact with the tube 34to positively displace liquid in the tube through the tube and the cammechanism keep the tubing from walking through the pump as the tubing 34is engaged by roller 16.

The present invention, can of course be employed in a number of contextsbut finds particular utility with regard to medical practice and thepumping of biological and therapeutic fluids. The present invention isparticularly advantageous in its quick and easy manipulation to permitinsertion or removal of the flexible tubing which carries the fluidsbeing pumped. As can readily be ascertained from the drawings, thedevice of the invention can in fact be opened and closed with the use ofonly a single hand and does not require any disassembly or reassemblyprocedures.

It will also be apparent that the present invention contemplates variousmodifications and variations which are considered to fall within thescope of the invention as defined in the claims presented herein.

What is claimed:
 1. A peristaltic pump comprising: a housing, means forimparting rotational motion through a shaft to roller assembly meansmounted on said housing for engaging and compressing a flexible tube tocontinuously displace fluid through said flexible tube, said flexibletube being held in contact with said roller assembly means by shoe meansmoveably mounted on said housing adjacent said roller assembly means andmoveable cam means positioned on each side of said roller assemblymeans, said cam means comprising a shaft, a cam assembly rotatablymounted on said shaft, spring means engaging said cam assembly urgingsaid cam assembly against said flexible tube, a second cam meansconnected to said shoe means moving said shoe means into a position ofengagement with said tubing, said shoe means comprising a body definingan arcuate surface for contacting said flexible tube when moved to aposition of engagement, said shoe means being adapted for displacementin one direction to engage a portion of said tube and hold it inengagement with said compressive roller assembly means or displacementin the other direction to disengage said tube from said roller assemblymeans and permit its removal from said pump.
 2. A peristaltic pumpcomprising: means for imparting rotational motion to a roller assemblyfor engaging and compressing a flexible tube to cyclically displacefluid in said tube, said roller assembly means comprising roller meansmounted within a housing disposed on a shaft connected to saidrotational motion means such that rotation of said shaft and housingcauses orbital rotation of said roller means around said shaft; saidroller assembly means being mounted on a pump housing, shoe meansmounted on said pump housing for movement thereon relative to said pumphousing to permit either displacement in a first direction to engage andhold a portion of said tube on said roller assembly means together withclamp means for intermittent engagement with said orbiting rollermeansor displacement in an opposite direction to the first direction todisengage from said flexible tube on said assembly means and permitremoval of said flexible tube from the pump housing, said clamp meanscomprising a pair of clamp assemblies spaced apart on either side ofsaid roller assembly means adapted to engage and hold a portion of saidtube keeping said tube from walking when engaged by said roller assemblymeans, said shoe means movement being effected by means of a movableshaft which is mounted to said shoe means.
 3. The peristaltic pump ofclaim 2 wherein said clamp means comprises a one piece rotatable cam andshaft, spring means mounted to said shaft engaging said cam toconstantly urge said cam toward said tubing.
 4. A peristaltic pump asclaimed in claim 3 comprising a body, a curved arm extending from saidbody and a plurality of knurles formed on the surface of said arm.
 5. Aperistaltic pump as claimed in claim 4 wherein said curved arm has afinger projections member extending outwardly from said arm.
 6. Aperistatic pum as claimed in claim 4 wherein a surface of said curvedarm has an abrasive coating.
 7. A peristaltic pump comprising a pumphousing, a roller assembly means mounted to said housing, said rollerassembly means being adapted to engage and compress a flexible tube tocontinuously displace measured equal units of fluid passed through saidtube, means to drive said roller assembly in a rotational manner, a shoemeans moveably mounted on said housing adjacent said roller assembly,means to drive said shoe means in one direction to engage a portion of aflexible tube when said flexible tube is placed in said roller assembly,locking means mounted on said pump housing on either side of said rollerassembly means, said shoe means being locked into position against saidflexible tube by said drive means and forming a lock when closed, saidshoe means comprising a body defining an arcuate inner surface adaptedto engage said flexible tube and forming a cresent shaped configurationwith the ends of the cresent being provided with a locking surfaceforming two lock points with said locking means holding said flexibletube in place thereby preventing the walking of the tube when the rollerassembly is rotated.
 8. A peristaltic pump as claimed in claim 7 whereinthe locking surfaces on the ends of the cresent are knurled.
 9. Aperistaltic pump as claimed in claim 7 wherein the locking surfaces onthe ends of the cresent have an abrasive coating.